Build a views filter to have a IN clause #drupal8

filter.php

<?php
/**
 * Created by PhpStorm.
 * User: jeromechevalier
 * Date: 29/10/2018
 * Time: 14:15
 */


namespace Drupal\portal_users\Plugin\views\filter;


use Drupal\user\Entity\User;
use Drupal\views\Annotation\ViewsFilter;
use Drupal\views\Plugin\views\filter\FilterPluginBase;
use Drupal\views\Plugin\views\join\JoinPluginBase;

/**
 * Class RetailerFilter
 *
 * This class automatically filter the view content  based on the value retailer_id of the user connected
 *
 * @ingroup views_filter_handlers
 *
 * @ViewsFilter("location_filter")
 *
 */
class LocationFilter extends FilterPluginBase
{


  /**
   * @return array
   */
  protected function operators()
  {
    $operators = [
        'IN' => [
            'title' => $this->t('Filter download by allowed site'),
            'method' => 'applyLocationFilter',
            'short' => $this->t('Allowed site only '),
            'values' => '1',
        ],
    ];
    return $operators;
  }


  function query()
  {

    $user = User::load(\Drupal::currentUser()->id());


    // Manage the fact that Retailer Administrator have an access to all retailer sites declare
    // for this reason we don't check inside user property, but load all available sites with the right Retailer ID
    if ($user->hasRole('retailer_administrator')) {
      $siteQuery = \Drupal::entityQuery('site_entity');
      $retailerID = \Drupal::service('portal_users.retailers_service')->getCurrentUserRetailerId();
      $siteQuery->condition('field_site_retailer',$retailerID);
      $sitesId = $siteQuery->execute();
    }
    else {
      $tempList = $user->get('field_user_sites')->referencedEntities();
      $sitesId = array();
      if (count($tempList) > 0) {
        foreach ($tempList as $site) {
          $sitesId[] = $site->id();
        }
      }
    }


    $sitesId = \Drupal::service('portal_users.retailers_service')->getAllowedLocationsId();
    $this->query->addField('download_forecast','id','',['function' => 'groupby']);     // Add the field to be able to do the group by SQL command
    $this->query->addTable('download_forecast__physical_location');
    // Filter download that correspond to an allowed site for the current user
    $this->query->addWhere($this->options['group'], 'download_forecast__physical_location.physical_location_target_id', $sitesId, 'IN');

  }

}

module_views.inc

<?php


/**
 * Implements hook_views_data().
 * Add the Retailer Filter to list of filter available for Views
 */
function portal_users_views_data()
{
  $data = [];

  $data['views']['location_filter'] = [
      'title' => t('Location Filter'),
      'filter' => [
          'title' => t('Filter to have only available site'),
          'group' => 'SRAI-Portal',
          'help' => t('Filter to have only available site'),
          'id' => 'location_filter'
      ],
  ];

  return $data;
}